ENTFACT-104

GROUND BEETLES

by Stephanie Bailey, Extension Entomologist
University of Kentucky College of Agriculture

Ground beetles make up one of the largest groups of beetles in North America, with more than 2200 species. Although there is some variation in their body shape and coloring, most are shiny and black (some are metallic), and have ridged wing covers. Another characteristic common to ground beetles is a smaller head than thorax, and threadlike antennae.

They may be confused with cockroaches such as the oriental roach (both are shiny and very dark) but beetles have hardened front wings where roaches either have leathery wings or no wings.

Adults are active at night and tend to hide under rocks during the day. They will run when exposed. They come out at night to feed o unsuspecting insects. Likely targets include caterpillars, root maggots, snails, and other soft bodied insects. The fiery searcher, a very brilliantly colored ground beetle, was imported to assist in the control of gypsy moth larvae Most species do not use their wings, but a few may fly to lights at night.

One group of ground beetles, called bombadier beetles, have an interesting defensive mechanism. When threatened, they raise the end of their body and fire a chemical gas with popping sound and smokelike puffs. The gas is irritating to enemies such as toads and would-be collectors.

Ground beetle larvae, like adults, are important predators. The larvae live below ground, where they use their large pincher-like mandibles to devour soil-dwelling insects.

Adults may wander into homes by crawling through small openings or under doors. They will not stay inside-they prefer the outdoors. Since ground beetles are beneficial insects, control is not warranted. However, if they are creating a nuisance, move or remove hiding places next to the house such as log piles, mulch, and debris around the perimeter. Caulking and weatherstripping will close some entrance points. Beetles found indoors may be swept up and discarded. If beetles are creating a nuisance by flying to lights at night, repositioning the lighting or changing white lights to yellow may reduce the attraction.

Read more about ground beetles and see pictures of different species at the Kentucky Critter Files.

Revised: 8/93

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